(From Cutler, 1994, Migotto and Ditadi, 1988, and Stephen and Edmonds, 1972)
Introvert nearly as long as the trunk.
Six to 12 stubby tentacles surround the nuchal organ.
On the distal part of the introvert bidentate compressed hooks are arranged in rings. Scattered on the posterior portion of the introvert are dark conical hooks, with a nearly circular cross section and a gentle posterior curve (conical hooks type C according Cutler, 1994).
The anal shield is ungrooved.
The caudal shield is not well developed, and in many worms is barely discernible.
The longitudinal muscle layer on the trunk wall is often split in the area under the anal shield.
The intestine is normally in a helical coil, whichmay appear loosely formed in some specimens. A spindle muscle fixes the intestine anteriorly and posteriorly.
Rectal caecum can be present in some worms.
Nephridia are reddish-brown, about as long as the trunk and attached for their whole length.
A pair of retractor muscles originates about 85-95% of the distance to the posterior end of the trunk.
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